Storage holds data, instructions, and information for future use on physical storage media like hard disks, optical discs, flash memory. There are three main types of storage media: magnetic storage including hard disks and floppy disks, optical storage like CDs and DVDs, and flash memory storage like solid state drives, memory cards, and USB flash drives. Storage capacity differs between media, with hard disks holding terabytes, optical discs holding gigabytes, and flash memory ranging from megabytes to gigabytes depending on the device. Memory and storage differ in that memory holds data temporarily during processing while storage holds data permanently when not in use.

1. At the end of this topic, students
should be able to:
a)
b)
c)
Identify storage media
Explain the functions of storage media
Differentiate between memory (RAM) and
storage
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Computer System
2.5.5 Storage
Chapter
PDT - 2017/2018

2. Storage
Storage holds data, instructions, and
information for future use
A storage medium / media is the physical
material on which a computer keeps data,
instructions, and information
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3. Define Storage Device
● A storage device is the computer hardware that records and/or
retrieves items to and from storage media
● It’s function is to store data and programs when they are not
being processed
● Stores data permanently
● Available in the form of hard disk, CD, USB drive. etc
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4. Reading is the process of
transferring items from a storage
medium into memory
Writing is the process of
transferring items from memory to
a storage medium
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5. Types of Storage
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● Magnetic Storage
● Optical Storage
● Flash Memory
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6. Magnetic Storage
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Type Description
Magnetic
storage
- Uses different patterns of magnetization
on a magnetically coated surface to store
information
- Eg :
Hard disk Floppy disk
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7. Magnetic Storage : Hard Disk
•
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7
A hard disk contains one or more inflexible,
circular platters that use magnetic particles to
store data, instructions and information.

8. Hard Disks
An external hard disk is a separate free-
standing hard disk that connects to your
computer with a cable or wirelessly
A removable hard disk is a hard disk
you insert and remove from a drive
that
Internal and
in miniature
external hard disks are available
sizes (miniature hard disks)
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9. – Stores information in deformities on the surface of
a circular disc and reads this information by
andilluminating the surface with a laser diode
observing the reflection.
– Types of optical disc are:
» Compact Disc (CD)
» Digital Video Disc
» Blu-ray Disc (BD)
(DVD)
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Optical Discs Storage
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10. A CD-ROM can be read from but not written to
• Read from a CD-ROM drive or CD-ROM player
A CD-R is a multi session optical disc
on
users can write, but not erase
which
A CD-RW is an erasable multisession
• Must have a CD-RW drive
disc
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Optical Discs Storage

11. Optical Discs Storage
A DVD-ROM is a high-capacity optical disc on
which users can read but not write or erase
• Requires a DVD-ROM drive
A Blu-ray Disc-ROM (BD-ROM)
capacity of 100 GB
has a storage
DVD-RW, DVD+RW, and DVD+RAM are high-
capacity rewritable DVD formats
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12. Flash Memory Storage
•
Flash memory chips are a type of solid state
media and contain no moving parts
Examples of flash
» Solid state drives
» Memory card
memory storage are:–
» USB flash drives
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13. Solid State
Drives
•
Solid state drives (SSDs) have several
over magnetic hard disks:
advantages
Generate less heat and
consume less powerFaster access time Faster transfer rates Last longer
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13

14. Solid state drives
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15. Memory card
•
A memory card is a removable flash memory
device that you insert and remove from a slot in a
computer,mobile device, or card reader/writer
Secure Digital
High Capacity
(SDHC)
CompactFlash
(CF)
Secure Digital
(SD) microSD
xD Picture
Card
Memory Stick
Micro (M2)microSDHC Memory Stick
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16. Flash Memory Storage
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17. USB flash drives
•
USB flash
computer
drives plug into a USB port on a
or mobile device
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Figure 7-21
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18. Storage Capacity Differences table:
( between magnetic, optical and flash memory )
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Types of Storage Media Examples Storage capacities
Magnetic disk External hard disks 2 TB or more
Internal hard disks 160 GB to 2TB
Removable hard disks 1 TB or more
Optical Disc DVD (1 Side-1 Layer) 4.7 GB
DVD (1 Side – 2 Layers) 8.5 GB
DVD (2 Sides-1 Layer) 9.4 GB
DVD (2 Sides-2 Layers) 17 GB
Blu-ray Disc (1 Side-1 Layer) 25 GB
Blu-ray Disc (1 Side-2 Layers) 50 GB
Blu-ray Disc (2 Sides-1 Layer) 50 GB
Blu-ray Disc (2 Sides-2 Layers) 100 GB
CD-ROM 650 MB to 1 GB
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19. 23
Typical of Flash Memory Storage
Storage Capacities
Solid State Drives(SSD) 16GB – 256GB
Memory cards
Compact Flash(CF)
Secure Digital(SD)
SDHC
XD Picture Card
512MB – 100GB
512MB – 8GB
4GB – 32GB
256MB – 2GB
USB Flash Drive 512MB – 100GB
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20. Compare Memory and Storage
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Memory (RAM) Storage
Hold data temporarily. Hold data permanently.
Hold programmable data , instruction and
processing data.
Hold data and information when they are not
being processed.
Memory are located on the motherboard. Storage are located outside the motherboard.
Data in the memory will be lost when the
power is turn off.
Data in the storage will not be lost when the
power is turn off.
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